Question: Expand.
Solution: $\begin{aligned} &\phantom{=}({d^2-3})(d^2+2) \\\\ &={d^2}(d^2+2){-3}(d^2+2) \end{aligned}$ $\begin{aligned} &=d^4+2d^2-3d^2-6 \\\\ &=d^4-d^2-6 \end{aligned}$